1. Technical Field
The present disclosure relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device capable of efficiently dissipating heat generated from a light emitting diode (LED) unit.
2. Discussion of the Related Art
A liquid crystal display comprises an LCD panel having a TFT substrate, a color filter substrate and a liquid crystal layer disposed therebetween. The LCD panel does not emit light by itself. Therefore, a backlight unit is disposed behind the LCD panel for providing light. The trarismittance of the light to the LCD panel depends on the alignment of liquid crystal molecules. The LCD panel and the backlight unit are enclosed within a chassis.
The backlight unit can be an edge type and a direct type. The two types are positioned differently in the backlight unit. The edge type backlight unit is typically employed in smaller-sized LCDs, such as, for example, display screens of laptop or desktop computers or a portable terminal apparatus. The edge type backlight unit comprises a light guiding plate disposed behind the LCD panel, a reflecting sheet disposed behind the light guiding plate, a lamp unit disposed along at least one side of the light guiding plate and providing light to the LCD panel, a lamp holder enclosing and holding the lamp unit, and optical sheets disposed on the light guiding plate for diffusing and focusing the light guided by the light guiding plate.
For the lamp unit, an Electro Luminescence (EL), a Cold Cathode Fluorescent Lamp (CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External Electrode Fluorescent Lamp (EEFL), or a Light Emitting Diode (LED) may be used.
The lamp holder formed in a ‘U’ shape encloses the lamp unit and can reduce light loss by reflecting light from the lamp unit to the light guiding plate. To reduce light loss in the opposite direction of the LCD panel, a reflecting sheet may be used and reflect light to the light guiding plate. By using the light guiding plate and the reflecting sheet, light emitted from the lamp unit is transformed to a surface light source incident upon the LCD panel.
When LEDs are used as a light source for the LCD, the LEDs are disposed on a substrate facing an incident surface of the light guiding plate, and the substrate and the LEDs are enclosed inside the lamp holder. As such, the heat generated from the lamp holder is trapped within the holder and is not easily dissipated to the outside.